We will develop and manufacture a nozzle assembly for the clinical flow- sorting of cells. The design has few parts, is inexpensive, and can be autoclaved or disposed of after use. The nozzle body will incorporate a closed-loop acoustic system offering superb droplet-formation stability. The acoustic system will lock-in the dominant resonance mode of the nozzle assembly, thereby fixing the droplet frequency without the need for an external reference clock. The nozzle will produce a diagnostic signal to ensure that the frequency, amplitude and phase of its vibration are stable and within the optimal range. These diagnostic features will allow nozzle clogs and stream instability to be detected. The early detection of changes in operating conditions will allow corrective intervention before anomalous operation leads to sorting errors. The nozzle assembly will include the necessary fluid lines and check valves to ensure sterility of the sample. We will design adapter brackets to mount the new nozzle in existing cell sorters. The commercial availability of an inexpensive, disposable nozzle assembly will represent a major step in the development of a high-speed cell sorter for clinical applications. PROPOSED COMMERCIAL APPLICATION: The new nozzle will be the most reliable, most easily sterilized, and lowest cost nozzle available. Because it will be approximately one-fifth the price of other commercially available units, it will be in demand as a disposable replacement unit for cost-effective clinical use with the approximately 4000 cell sorters that exist world wide. For less critical samples, the nozzle will be autoclavable, enhancing its utility for molecular biology research. Finally, it will offer much greater reliability, decreasing the calibration burden for sorter operators.